TAOISEACH Micheál Martin expressed his gratitude to Joe Biden for the president's "unwavering support" of the Good Friday Agreement in recent weeks.
During their virtual St Patrick's Day meeting on Wednesday, Biden said that the US would continue in its "strong" support of both the Agreement and of Ireland.
It's understood that Mr Martin thanked the president, telling him that his support " means a lot", particularly in light of Brexit negotiations.
Pressure has been placed on the relationship between Ireland, the UK and the EU ever since Britain voted to leave the union in 2016.
Things got particularly heated last month during a spat between the UK and the UK about the supply of AstraZeneca's Covid-19 vaccine.
But throughout it all, Biden and the US have always prioritised the integrity of the 1998 Belfast Agreement.
"You know my view, and the view of my predecessor, on the Good Friday Agreement," Biden told Martin.
"We strongly support [it], we think it's critically important [it is] maintained and the political and economical stability of Northern Ireland is very much in the interest of all of our people."
Martin responded saying: "It has meant a lot and it has mattered, including as we negotiated Brexit.
"With a new trading relationship now in place between the EU and the UK, and a Protocol that protects peace and avoids a hard border on this island, I want to move forward with a positive relationship with the United Kingdom.
"That means standing by what has been agreed and working together to make a success of it.
"That in turn, can help maintain peace and promote greater reconciliation on our shared island - goals that I know you support."
Martin also spoke with vice president Kamala Harris and House Speaker Nancy Pelosi during the meeting, and took part in the traditional handing over of the shamrock bowl with President Biden too.